According to CNN's Jill Martin, Ravens head coach John Harbaugh was informed of the decision on Thursday and released the following statement on Urschel: "We respect John and respect his decision. We appreciate his efforts over the past three years and wish him all the best in his future endeavors."

Urschelreleased a statement on the decision:

John Urschel @JohnCUrschel

https://t.co/UmIQa2kn5e

A source told ESPN's Jamison Hensley that the results of a recent chronic traumatic encephalopathy (CTE) study played a role in Urschel's retirement.

Urschel is pursuing his doctorate at the Massachusetts Institute of Technology.

The aforementioned study was published Tuesday in the medical journalJAMA(h/t CNN.com'sDaniella Emanuel). Doctors discovered CTE in 110 of 111 brains from deceased former NFL players.

Urschel is a mathematician, and he said the head trauma after a 2015 concussion impacted his ability to think, according to Hensley: "I think it hurt my ability to think well mathematically. It took me about three weeks before I was football-ready. It took me a little bit longer before my high-level visualizations ability came back."

The Ravens selected Urschel in the fifth round of the 2014 NFL draft out of Penn State. The team utilized him primarily as a backup guard, although he also made appearances at tackle and center. He made 13 starts during his three-year career.

Prior to his retirement, Urschel was in the mix for Baltimore's starting job at center. Ryan Jensen and Matt Skura will now compete for the spot.